Dominic Thiem came from a set down to beat John Isner and reach the semi-finals of the Madrid Open on Friday.  The Austrian could face 13-time French Open champion Rafael Nadal in the last four after recovering against Isner to win 3-6, 6-3, 6-4. 

Nadal plays fifth seed Alexander Zverev in his quarter-final later on Friday. 

A showdown between Thiem and Nadal would be a repeat of the 2018 and 2019 French Open finals, both of which were won by Nadal. 

Zverev, meanwhile, was on the losing side in the final when Thiem clinched his first grand slam title at last year's US Open, when he beat the German in five sets. 

The world number four will be one of Nadal's fiercest challengers at Roland Garros next month and if he meets the Spaniard in Madrid, it will be taken as an early gauge of his credentials. 

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After twice finishing as runner-up in Madrid, Thiem will be hoping to go one step further this year but he is in the tougher half of the draw. 

In the other quarter-finals, the unseeded pair of Alexander Bublik and Casper Ruud will face off to meet either eighth seed Matteo Berrettini or 16th seed Cristian Garin in the semis.

The 36-year-old Isner has never been at his most comfortable on clay but he caught Thiem cold at the Caja Magica by breaking early to claim the opening set. 

But Thiem ripped a forehand pass to open up a break opporunity at 3-2 in the second, which he took when Isner hit the net with a volley. 

Thiem was reading Isner's serve better by the time the match went to a decider but it was not until 4-4 that he struck again, when he chased down three Isner volleys to serve for victory. 

He closed out, a forehand volley securing victory in just under two hours. 

"He's one of the best servers in history, especially here in the altitude, it bounces high and it's so difficult to return," said Thiem afterwards. 

"To start with a break down is almost like losing the first set but I stayed focused, kept a good fifghting spirit. Very few points decide that kind of game and that's how I turned things around in the second set." 

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